Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is a disease which can result in death and is characterized by increased pulmonary artery pressure and pulmonary vascular resistance. A need exists for better compounds and methods for treating PH and PAH. See, for example, US Patent Publication No. 2013/0274261. Many valuable pharmacologically active compounds, including some of interest with respect to PH and PAH, cannot be effectively administered orally for various reasons and are generally administered via intravenous or intramuscular routes. These routes of administration generally require intervention by a physician or other health care professional, and can entail considerable discomfort as well as potential local trauma to the patient. One example of such a compound is treprostinil and derivatives thereof, which has been used in the treatment of PH and PAH. See, for example, WO 2005/007081. The core chemical formula is (herein also labeled, Compound A):
including pharmaceutically acceptable salts such as the sodium salt.
Accordingly, there is a clinical need in providing treprostinil by improved formulations and methods, e.g., either orally or transdermally. More particularly, there is a need for a safe and effective method for increasing the systemic availability of treprostinil via administration of treprostinil or treprostinil analogs.
The application of transdermal drug delivery technology to the administration of a wide variety of drugs has been proposed and various systems for accomplishing this are disclosed in numerous technical journals and U.S. Pat. Nos. 3,598,122, 4,144,317, 4,201,211, 4,262,003, and 4,379,454, all of which are incorporated herein by reference, are representative of various transdermal drug delivery systems of the prior art, which systems have the ability of delivering controlled amounts of drugs to patients for extended periods of time ranging in duration from several hours to several days. None of the above patents nor any other prior art of which the inventors are aware describes a transdermal delivery system which is intended to deliver treprostinil or its derivatives nor are they aware of data on skin permeability or therapeutic transdermal delivery rates adequate to design such a system.